package cn.dzz.servlet;

import javax.imageio.ImageIO;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;

/**
 * @author ArkD42
 * @file OA
 * @create 2020 - 06 - 18 - 10:01
 */

@WebServlet("/verify")
public class VerificationCodeServlet extends BaseServlet{

    /**
     * /verify?act=genImage
     * @param request
     * @param response
     * @throws IOException
     */
    public void genImage(HttpServletRequest request, HttpServletResponse response) throws IOException {
        // 设置图片的宽高
        int width = 60, height = 20;

        // 创建具有可访问图像数据缓冲区的Image
        BufferedImage bufferedImage = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);
        Graphics2D graphics2D = bufferedImage.createGraphics();

        // 创建一个随机数生成对象
        Random random = new Random();

        graphics2D.setColor(Color.WHITE);
        graphics2D.fillRect(0, 0, width, height);

        // 创建字体，字体的大小应该根据图片的高度来定
        Font font = new Font("微软雅黑", Font.PLAIN, 18);

        // 设置字体
        graphics2D.setFont(font);

        // 画边框
        graphics2D.setColor(Color.BLACK);
        graphics2D.drawRect(0, 0, width - 1, height - 1);

        // 随机产生160条干扰线
        graphics2D.setColor(Color.LIGHT_GRAY);
        for (int i = 0; i < 160; i++) {
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            int x1 = random.nextInt(12);
            int y1 = random.nextInt(12);
            graphics2D.drawLine(x, y, x + x1, y + y1);
        }

        // randomCode 用于保存随机产生的验证码
        StringBuffer randomCode = new StringBuffer();
        int red = 0, green = 0, blue = 0;

        // 随机产生4位数字的验证码
        for (int i = 0; i < 4; i++) {
            // 得到随机产生的验证码数字
            String strRand = String.valueOf(random.nextInt(10));

            // 产生随机的颜色分量来构造颜色值
            red = random.nextInt(110);
            green = random.nextInt(50);
            blue = random.nextInt(50);

            // 用随机产生的颜色将验证码绘制到图像中
            graphics2D.setColor(new Color(red, green, blue));
            graphics2D.drawString(strRand, 13 * i + 6, 16);

            randomCode.append(strRand);
        }

        // 将四位数字的验证码保存到session中
        request.getSession().setAttribute("randomCode", randomCode.toString());
        System.out.println(this.getClass().getName() + " 生成的验证码：" + randomCode.toString());

        // 禁止图像缓存
        response.setHeader("Pragma", "no-cache");
        response.setHeader("Cache-Control", "no-cache");
        response.setDateHeader("Expires", 0);

        response.setContentType("image/jpeg");
        // 将图像输出到servlet输出流中
        ServletOutputStream sos = response.getOutputStream();
        ImageIO.write(bufferedImage, "jpeg", sos);
        sos.close();
    }

}
